1. Field of the Invention
The present invention relates to a key for use in a piano and so on, and more particularly, to a key which has a weight attached thereto to provide a desired touch load.
2. Prior Art
FIG. 1 illustrates a conventional key (white key) for a grand piano. This key 51 is comprised of an elongated key body 52 made of wood and having a rectangular cross section; a white key cover 53 made of plastic covering a front region of the key body; a plurality (three in this example) of weights 54 attached on a side face of the key body 52; and so on. The key body 52 is swingably supported by a balance pin (not show) at the center thereof, and an action (not shown) is carried thereon in a region behind the balance pin. FIG. 2 illustrates a conventional black key, the configuration of which is basically identical to that of the white key. A sharp key cover 58, which is made of plastic, is formed with a recess open to below, and is adhered to a front region of the top face of the key body 52 to cover the same.
The weights 54 are attached to provide a desired touch load (static load) for the key, and are each made of lead of a predetermined size molded into a cylindrical shape. On the other hand, the key body 52 is formed with three circular embedding holes 55 of a predetermined size which laterally extend through the key body 52 at predetermined positions in a front region thereof. The weights 54 are filled in these embedding holes 55, and then caulked for attachment to the key body 52. The lead is employed as the weights 54 in this manner because the lead has a high specific gravity (approximately 11.3) among metals, is inexpensive, and exhibits high flexibility and ductility which facilitate works as mentioned above.
Generally, the touch load may be adjusted after the weights 54 have been attached as described above for purposes of eliminating variations in touch load among keys and of matching the touch load for a player""s preference. For adjusting the touch load, a side face of a weight 54 is cut away for reducing the touch load since the weight 54 is attached by caulking and therefore removed with difficulties. On the other hand, for increasing the touch load, at least one of previously provided separate adjusting weight 56, made of lead, is additionally attached to the key body 52, as indicated by broken lines in FIG. 1, for the same reason. In this event, a position for attaching the adjusting weight 56 is first determined such that the moment imparted by the adjusting weight 56 about the balance pin is appropriately produced in accordance with the touch load to be added. Then, an embedding hole 57 is additionally formed at the determined attaching position on the key body 52, followed by caulking the adjusting weight 56 for attachment. These works are performed for each key 51.
In the conventional key 51 described above, lead is used as the material for the weights 54 for the reasons mentioned above. However, since lead is an injurious material, it is desirable that lead is used for the weights of the keys as least frequently as possible, so that an alternative material is needed for substitution for lead. Also, since the conventional key 51 involves caulking for attaching the weights 54 to each key body 52, this work itself is laborious. Also, due to difficulties in removal of the weights 54 attached by caulking, and due to the constant specific gravity of the weights 54, the adjustment of the touch load involves the works which include cutting away the side face of a weight 54, forming an embedding hole 57 into the key body 52 while determining a position at which an adjusting weight 56 is attached, and attaching the adjusting weight 56 for each key 51, as described above. As a result, the adjusting works require significant efforts, resulting in an increase in the manufacturing cost. Further, the attachment of the adjusting weight 56 requires the formation of the embedding hole 57 laterally extending through the key body 52, in addition to the original embedding holes 55, thereby giving rise to a problem that the strength of the key body 52 tends to be insufficient.
It is an object of the present invention to solve the problems as mentioned, and specifically to provide a key which is capable of facilitating the attachment of a weight, and adjustments of a touch load, while using an alternative material for substitution for lead as a material for the weight, thereby reducing the manufacturing cost.
To achieve this object, a key according to a first invention is characterized by comprising a swingable key body formed with an embedding hole; and a weight made of a composite material produced by blending a plurality of kinds of materials except for lead in a predetermined blending proportion so as to have a predetermined specific gravity, and removably attached to the embedding hole of the key body.
According to this key, the weight is made of a composite material produced by mutually blending a plurality of kinds of materials except for lead in a predetermined blending proportion, and removably attached to the embedding hole formed in the key body to add a weight to the key body. In this case, the specific gravity of the entire composite material thus blended can be made equivalent to that of lead by using, for example, a suitable high specific gravity metal as one of the materials except for lead. Therefore, the composite material thus composed can be used as an alternative material for the weight for substitution for conventionally used lead. Also, since the weight made of the composite material can be removably attached to the embedding hole, the attachment and removal of the weight can be readily carried out as compared with the conventional one which is caulked for attachment.
In this case, preferably, one of the plurality of kinds of materials comprises an elastic material, so that the weight has elasticity, and is removably attached to the embedding hole of the key body through press fitting.
In this configuration, the weight made to have elasticity given by one of the materials comprising an elastic material can be attached to the embedding hole through simple press fitting, so that the attachment and removal of the weight become more easy than the conventional caulked one, thereby making it possible to reduce the manufacturing cost by simplifying the works involved in attaching the weight.
In this case, preferably, the elastic material comprises rubber, and another one of the plurality of kinds of materials comprises powdered tungsten.
Tungsten is harmless and has a very large specific gravity (approximately 19.3), so that it is particularly suitable for achieving a specific gravity in a required range which includes a specific gravity equivalent to lead, with a blend of rubber. Also, since the rubber, which comprises an elastic material, serves to ensure the elasticity of the weight, and is relatively inexpensive, the material cost can be reduced correspondingly.
In these cases, preferably, the weight comprises a plurality of types of weights made by blending the elastic material and the other one of the plurality of kinds of material in different blending proportions from one another to have different specific gravities from one another.
In this configuration, since the weight comprises a plurality of types of weights having different specific gravities, the weight can be made different without changing the size thereof. Therefore, for example, the touch load can be readily adjusted by previously providing a plurality of weights having the same shape and size as one another and different weights, and selecting one having an appropriate weight from these weights for attachment to the embedding hole. This results in complete elimination of the cutting of the weight for reducing the touch load, and the additional provision and positioning of an embedding hole and a weight for adjustment for increasing the touch load in the prior art. The key manufacturing cost can be further reduced correspondingly by the omission of such laborious works for adjusting the touch load. Also, since no embedding hole for adjusting the touch load need be additionally formed, it is possible to prevent a degraded strength of the key body which would otherwise result therefrom.
In this case, preferably, the key body comprises a plurality of key bodies which are formed with the embedding holes of a shape and a size identical to one another, respectively, wherein the plurality of types of weights have the shape and size identical to one another, so that they can be removably press fitted into the embedding holes.
In this configuration, weights having optimal weights, selected from the plurality of weights, can be attached to the embedding holes previously formed in the plurality of key bodies to have the same shape and size. Therefore, unlike the prior art, the touch load can be more readily adjusted, resulting from the fact that the position and size of the embedding hole need not be determined for each key.
Alternatively, it is preferable that the key further comprises a weight attaching member made of an elastic material in the shape of a sleeve having an inserting hole, wherein the weight is fitted into the inserting hole of the weight attaching member, and removably fitted into the embedding hole of the key body through the weight attaching member.
In this configuration, the weight is fitted into the inserting hole in the sleeve-shaped weight attaching member made of an elastic material, and is removably fitted into the embedding hole of the key body, taking advantage of the elasticity of the weight attaching member. In this way, the weight can be readily attached to the embedding hole of the key body through simple press fitting, so that the attachment and removal of the weight is made easier than the conventional caulked one to simplify the works involved in the attachment of the weight, thereby making it possible to reduce the manufacturing cost.
In this case, preferably, the plurality of kinds of materials include powdered tungsten and plastic, and the elastic material comprises rubber.
This configuration provides the advantage of tungsten which is harmless and has a very high specific gravity. Also, the rubber, which comprises an elastic material, serves to ensure the elasticity for removably fitting the weight attaching member and the weight, and is relatively inexpensive, thereby making it possible to reduce the material cost correspondingly.
In these cases, preferably, the weight comprises a plurality of types of weights which are made of a composite material produced by blending the plurality of kinds of materials except for lead in different blending proportions from one another so as to have different specific gravities from one another, and have a size and a shape identical to one another.
In this configuration, the plurality of types of weights have the size and shape identical to one another, and differ from one another in the blending proportion of the plurality of kinds of materials, of which they are made, to have different specific gravities and hence weights from one another. It is therefore possible to readily adjust the touch load by selecting one having an optimal weight from the plurality of types of weights.
Also, to achieve the aforementioned object, a key according to a second invention is characterized by comprising a swingable key body formed with an embedding hole; and a weight fitted in the embedding hole of the key body, wherein the weight has a weight attaching member made of heat shrinkable plastic in the shape of a sleeve having a predetermined size, and a weight body made of a predetermined metal material except for lead in the shape of a cylinder having a predetermined size, accommodated in the thermally shrunk weight attaching member in close contact therewith.
According to this key, the weight has a weight attaching member made of heat shrinkable plastic in the shape of sleeve and a weight body made of a predetermined metal material except for lead in a cylindrical shape. After the weight body is inserted into the weight attaching member, the weight attaching member is heated for shrinkage to bring the weight attaching member into close contact with the weight body, with the result that the weight is assembled with the weight body contained therein. Then, the assembled weight is inserted into the embedding hole formed in the key body for attachment thereto. In this case, the material in the foregoing composition can be used as an alternative material for substitution for lead by selecting a proper one having a high specific gravity as the metal material except for lead. Also, a noise reduction function, possessed by conventionally used lead itself, may be provided by selecting a heat shrinkable plastic which can absorb sound in a certain frequency range as the heat shrinkable plastic, of which the weight attaching member is made.
In this case, preferably, the heat shrinkable plastic has elasticity.
In this configuration, when the weight is fitted into the embedding hole of the key body, the weight can be readily attached while deforming the elastic weight attaching member through shrinkage. Also, after the attachment, the elastic return force of the weight attaching member keeps the weight in close contact with the embedding hole, thereby making it possible to prevent trembling of the weight and noise resulting therefrom.
Further, to achieve the aforementioned object, a key according to a third invention is characterized by comprising a swingable key body formed with an embedding hole; and a weight made of a molded composite material produced by blending a metal except for lead and plastic in a predetermined blending proportion to have a predetermined specific gravity, and embedded in the embedding hole to be attached to the key body, wherein the embedding hole is formed in a circular hole, and the weight is formed in the shape of a cylinder which can be press fitted into the embedding hole, and has a convex element on the outer peripheral face thereof to reduce a frictional resistance when the weight is press fitted into the embedding hole.
According to this key, the weight is made of a molded composite material produced by blending a metal except for lead and plastic in a predetermined blending proportion, and embedded in the embedding hole for attachment to the key body. In this case, the composite material in the foregoing composition can be used as an alternative material for substitution for lead by selecting a proper one having a high specific gravity as the metal material except for lead. Generally, a composite material produced by blending a metal and plastic has characteristics that it is not so ductile as lead, and is vulnerable to an impact. Therefore, as in the present invention, the convex element formed on the outer peripheral face of the weight facilitates the press fitting of the weight into the embedding hole by alleviating a frictional resistance when the weight is press fitted into the embedding hole. In addition, even when the weight is attached by caulking or the like, an impact at that time is reduced so that the weight can be made less susceptible to a failure and so on.
In this case, preferably, the metal except for lead comprises powdered tungsten, and the plastic comprises nylon.
This configuration provides the advantage of tungsten which is harmless and has a very large specific gravity. Also, nylon is relatively tough and highly impact resistant among plastic. Therefore, by employing nylon as a base resin, it is possible to ensure such characteristics that are required for the weight. Also, since nylon is apt to injection molding, the weight can be readily molded into a desired shape.
Also, preferably, the weight comprises a plurality of types of weights made of a plurality of kinds of composite materials having different specific gravities from one another, produced by blending the metal except for lead and the plastic in different blending proportions from one another.
In this configuration, since the weight comprises a plurality of types of weights having different specific gravities, a different weight can be provided without changing their sizes. It is therefore possible to readily adjust the touch load by selecting one having an optimal weight from the plurality of types of weights.
Also, preferably, the convex element comprises a plurality of protrusions formed on the outer peripheral face of the weight and spaced apart from one another.
In this configuration, the plurality of protrusions formed as the convex element on the outer peripheral face of the weight can alleviate the frictional resistance when the weight is press fitted into the embedding hole, and provide the resulting effects mentioned above. Particularly, since the caulking effect can be ensured, the weight can be securely attached to the key body.
In the alternative, the convex element preferably comprises two flanges formed on both ends of the outer peripheral face of the weight along the circumferential direction.
According to this configuration, the two flanges formed as the convex element on both ends of the outer peripheral face of the weight can alleviate the frictional resistance when the weight is press fitted into the embedding hole, and provide the resulting effects mentioned above. Particularly, since the caulking effect can be ensured, the weight can be securely attached to the key body.
Further alternatively, the convex element preferably comprises a plurality of elastic protrusive pieces arranged on both ends of the outer peripheral face of the weight and spaced apart from each other in the circumferential direction, wherein the elastic protrusive pieces extend outward in the axial direction, and stuck out in a radial direction.
In this configuration, the plurality of elastic protrusive pieces formed as the convex element can alleviate the frictional resistance when the weight is press fitted into the embedding hole. Also, the weight can be snap fitted into the embedding hole, taking advantage of the elasticity of the protrusive pieces, so that the weight can be securely attached to the key body without caulking.
Further alternatively, the convex element preferably comprises a plurality of circumferentially extending larger diameter portions arranged at positions except for both ends of the outer peripheral face of the weight, and spaced apart in the axial direction.
In this configuration, the plurality of larger diameter portions as mentioned, formed as the convex element, can alleviate the frictional resistance when the weight is press fitted into the embedding hole. Also, since the plurality of larger diameter portions are positioned in a central region of the outer peripheral face of the weight, the caulking effect can be further enhanced, thereby making the weight less susceptible to a failure and so on due to an impact, as compared with the aforementioned weight which has the flanges formed on both ends.
Further alternatively, the convex element preferably comprises a large number of axially extending convex bars arranged on the outer peripheral face of the weight, and spaced apart in the circumferential direction.
In this configuration, the large number of convex bars as mentioned above, formed as the convex element, can alleviate the frictional resistance when the weight is press fitted into the embedding hole. Also, since the large number of convex bars are disposed in the circumferential direction and extend in the axial direction to make the weight prone to shrinkage and deformation, the caulking and so on are facilitated, and an impact is reduced during the caulking, thereby making the weight less susceptible to a failure.
Further, to achieve the aforementioned object, a key according to a fourth invention is characterized by comprising a swingable key body having a rectangular cross section, extending in the longitudinal direction, and formed with a recess in a front region of the top face thereof and along the same; a plate-shaped weight made of a composite material produced by blending a plurality of kinds of materials except for lead having different specific gravities from one another, accommodated in the recess of the key body to impart a weight to the key body; and a key cover attached on the front region of the key body so as to cover the weight.
According to this key, the weight is formed in the shape of plate from a composite material produced by blending a plurality of kinds of materials except for lead having different specific gravities, and is accommodated in the recess formed along the front region of the top face of the key body. In this case, for example, by using a proper metal having a high specific gravity as one material except for lead and using plastic as another material, the specific gravity of the whole blended composite material can be a large specific gravity equivalent or approximate to that of lead. Also, the weight, in a plate shape, can be disposed in the longitudinal direction along the recess of the key body. It is therefore possible to sufficiently ensure the weight of the weight, so that the composite material in the above composition can be used as an alternative material for substitution for conventionally used lead.
Also, unlike the prior art, the weight is attached to the key body by accommodating it in the recess formed in the top face thereof to eliminate a work for forming an embedding hole for attaching the weight, and a work for caulking the weight, so that the manufacturing cost can be reduced as a result of the simplification of the attaching works. Since the attached weight is covered with the key cover, the outer appearance of the key will not be affected at all.
In this case, preferably, the key body is formed with an embedding hole on a side face of the key body at a longitudinal position determined in accordance with a touch load given by the weight, and the key further comprises a weight for adjustment embedded in the embedding hole for adjusting the touch load.
According to this configuration, a longitudinal position of the key body is determined in accordance with a touch load provided in a state in which the plate-shaped weight is attached, and an embedding hole is formed on the side face of the key body at the determined position. Then, a weight for adjustment having a predetermined weight is fitted to adjust the touch load. Since the weight for adjustment is also made of a material except for lead, the weight for the key, together with the plate-shaped weight, can be made without using any lead.
Also, since the weight is disposed only near the top face of the key body and does not exist in a lower portion, the weight for adjustment can be attached at a determined desired attaching position, without being interfered by an existing weight, unlike the prior art. As a result, the touch load can be efficiently adjusted without changing the weight or attaching position of the weight for adjustment.
Further, for example, the touch load can be readily adjusted only with a single weight for adjustment by setting the plate-shaped weight to such a weight as to burden a majority of a weight which should be given to the key body. Also, in this case, since only one embedding hole need be formed, a degraded strength of the key body, caused by the formation of the embedding hole, can be limited to a minimum.
Alternatively, the weight preferably comprises a plurality of types of weights having different weights from one another.
In this configuration, the touch load can be readily adjusted only with the plate-shaped weight by selecting a single weight having an optimal weight from the plurality of types of weights having different weights. Also, since no embedding hole is required, the strength of the key body can be sufficiently maintained.
In this case, preferably, the plurality of types of weights are respectively made of composite materials having different specific gravities from one another, produced by blending the plurality of kinds of materials in different blending proportions from one another, and have a size and a shape identical to one another complementary to the recess of the key body.
In this configuration, it is possible to readily provide a plurality of types of weights which are identical in size and shape and different in weight due to the difference in specific gravity. Also, since the weight is formed complementarily to the recess of the key body, any weight can be exactly fitted into the recess, thereby making it possible to attach the weight to the key body without trembling.
Further, to achieve the aforementioned object, a key according to a fifth embodiment is characterized by comprising a swingable key body; a sharp key cover having a cavity open to below, and attached on the top face of the key body; and a weight made of a composite material produced by blending a plurality of kinds of materials except for lead having different specific gravities from one another, and accommodated in the cavity of the sharp key cover to impart a weight to the key body.
According to this key, the weight is made of a composite material produced by blending a plurality of kinds of materials except for lead, and is accommodated in the cavity of the sharp key cover. In this case, for example, by using a proper metal having a high specific gravity as one material except for lead and using plastic as another material, the specific gravity of the whole blended composite material can be equivalent to that of lead, or lie in a predetermined range including the specific gravity equivalent to that of lead. It is therefore possible to use the composite material in the above composition as an alternative material for substitution for conventionally used lead.
Also, since the weight is accommodated in the cavity of the sharp key cover for attachment, thus eliminating the conventional work for forming an embedding hole and work for caulking the weight, the manufacturing cost can be reduced correspondingly by a reduction in the number of steps for these works. As mentioned above, the sharp key cover is generally formed with a cavity, and such a cavity is utilized as it is for accommodating the weight, so that any change in the design of the sharp key cover is not required, and any increase in cost does not arise therefor. Also, the absence of the embedding hole formed in the key body can maintain the strength of the key body.
In this case, preferably, the weight is molded into a predetermined size and shape corresponding to the cavity of the sharp key cover, and fitted in the cavity.
In this configuration, since the weight is exactly fitted in the cavity of the sharp key cover and attached in this state, the weight can be prevented from trembling in the sharp key cover when the black key swings, so that a smooth operation of the black key can be ensured.
In these cases, preferably, the weight comprises a plurality of types of weights having different weights from one another.
In this configuration, the touch load can be readily adjusted by selecting a single weight having a required weight from the plurality of types of weights having different weights. This result in complete elimination of the cutting of the weight, and the additional provision and positioning of an embedding hole and a weight for adjustment for increasing the touch load in the prior art. The black key manufacturing cost can be further reduced correspondingly by the omission of such laborious works for adjusting the touch load.
In this case, preferably, the plurality of types of weights are respectively made of composite materials having different specific gravities from one another, produced by blending the plurality of kinds of materials in different blending proportions from one another.
In this configuration, it is possible to readily provide, for example, a plurality of types of weights which are identical in size and shape and different in weight due to the difference in specific gravity. Therefore, the touch load can be smoothly adjusted since the attachment of the weight to the recess of the sharp key cover can be performed in a similar manner with any of the plurality of types of weights.
Alternatively, the plurality of types of weights preferably have different sizes from one another.
In this configuration, a plurality of types of weights having different weights can be readily provided, for example, by only changing the size (for example, the length) without changing the specific gravity of the composite material, so that the touch load can be smoothly adjusted.